JPH11158110A - Iron phosphate-oxalic acid composite compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an iron phosphate compound having a catalytic function or the like. SOLUTION: This compound is an iron phosphate-oxalic acid composite compound shown by the general formula FePO4 .x(H2 O)2 .y(COX)2 (X is a hydroxyl, alkoxyl or O-M group; M is an alkaline metal atom or NH4 group; (x) is an integer of 0 to 4; and (y) is an integer of 1 to 4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel iron phosphate compound (that is, an iron phosphate-oxalic acid composite compound) useful as a catalyst or the like.

[0002]

2. Description of the Related Art Tridymite (T
ridymite type iron phosphate (iron orthophosphate: F)
ePO ₄ ), quartz (Quartz) type iron phosphate (iron orthophosphate: FePO ₄ ), iron phosphate [Fe ₃ (P ₂ O ₇ ) ₂ ] in which iron is partially reduced, and iron is reduced to divalent. Iron phosphate (iron pyrophosphate: Fe ₂ P ₂ O ₇ ) is generally known, and furthermore, amorphous (Amorphou)
Iron phosphate of the s) type (iron orthophosphate: FePO ₄ ) is also known. These iron phosphates are used, for example, as catalysts.

[0003]

A novel iron phosphate compound having a catalytic function or the like has not been known, and such a novel iron phosphate compound is desired. That is, an object of the present invention is to provide a novel iron phosphate compound having a catalytic function and the like.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to provide an FeP.
An iron phosphate-oxalic acid complex compound represented by a general formula of O ₄ .x (H ₂ O) ₂ .y (COX) ₂ (wherein X represents a hydroxyl group, an alkoxy group, or an OM group; M represents an alkali metal atom or an NH ₄ group, x represents an integer of 0 to 4, and y represents an integer of 1 to 4).

[0005]

Novel iron phosphate compounds of the present invention DETAILED DESCRIPTION OF THE _{INVENTION, FePO 4 · x (H 2} O) 2 · y (COX) iron phosphate represented by ₂ becomes the general formula - oxalic acid complex compound ( In the formula, X represents a hydroxyl group, an alkoxy group, or an OM group,
M represents an alkali metal atom or an NH ₄ group;
And y represents an integer of 1 to 4), elemental analysis, FT-IR spectrum, and thermal analysis (TG-DT
A), X-ray diffraction spectrum, redox titration (measurement of Fe valence), and the like.

[0006] Among the novel iron phosphate compounds of the present invention, F
ePO_FourX (H_TwoO)_Two・ Y (COOH)_TwoBecome general
As the iron phosphate-oxalic acid complex compound represented by the formula,
For example, FePO_Four・ (COOH)_Two, FePO_Four・
(H_TwoO)_Two・ (COOH)_Two, FePO_Four・ 4 (H_Two
O)_Two・ 4 (COOH)_TwoAnd the like.
FePO_Four・ (H_TwoO)_Two・ (COOH)_TwoTable with formula
FT-IR spectrum, TG-DTA
Figures and X-ray diffraction spectra are shown in FIGS. _Four・
(COOH)_TwoFT-IR spectrum of a compound represented by the following formula:
Shows the spectrum, TG-DTA diagram and X-ray diffraction spectrum
4-6, FePO_Four・ 4 (H_TwoO)_Two・ 4 (COO
H)_TwoFT-IR spectrum of a compound represented by the formula:
TG-DTA diagram and X-ray diffraction spectrum are shown in Figs.
Shown respectively. Note that these are all based on redox titration.
The valence of Fe is trivalent.

[0007] FePO ₄ · x (H ₂ O) ₂ · y (COO
H) ₂ is an iron phosphate-oxalic acid complex compound represented by the general formula of FePO ₄ .2H ₂ O, which is preferably prepared by mixing iron phosphate and oxalic acid represented by the formula of Preferably from 20 to 100 ° C, particularly preferably from 30 to 1 ° C.
It can be produced by reacting at 00 ° C. The reaction pressure is preferably normal pressure, but is not particularly limited. This manufacturing method includes, for example, FePO _4.
A preferred method is to heat and stir iron phosphate represented by the formula 2H ₂ O in an aqueous oxalic acid solution. Generated F
_{ePO 4 · x (H 2 O} ) 2 · y (COOH) 2 is separated and washed, then dried at 70 to 200 ° C..

The above-mentioned FePO_Four・ 2H_TwoRepresented by the formula O
Ferric phosphate dihydrate (FePO4)
_Four・ 2H_TwoO) is specifically used, but FePO_Four・
(H _TwoO)_Two・ (COOH)_TwoIron phosphate-oxalic acid
In a reaction system for producing a composite compound, FePO_Four・ 2H_Two
Compounds that can form O can also be used. This
Such compounds include, for example, tridymite type and quartz
Type iron phosphate or iron pyrophosphate in the presence of water
What was done.

As the oxalic acid, oxalic anhydride or hydrous oxalic acid is used. These are FePO ₄ · 2
0.8 to 10 mol per mol of H ₂ O, and more are preferably 1-7 times moles. At this time, FePO ₄
By adjusting the ratio of oxalic acid to 2H ₂ O, different x and y can be obtained. For example,
Oxalic acid must be FePO ₄ .2 to obtain x = y = 1.
It is preferably used in an amount of 0.8 to 3 times, more preferably 1 to 2 times the mole of H ₂ O. To obtain x = y = 4, oxalic acid is added to FePO ₄ .2H ₂ O. And preferably 4 to 10 times, more preferably 4 to 7 times.
In addition, the drying temperature is 100 ° C. or more, and further 130 ° C.
As a result, water of crystallization is scattered, and x is 0 or close to 0. Oxalic acid is preferably used as an aqueous solution as described above, and the concentration of oxalic acid in the oxalic acid aqueous solution is 0.5 to 50% by weight, more preferably 5 to 30% by weight.
It is preferred that

[0010] Among the novel iron phosphate compounds, FePO ₄
X (H ₂ O) ₂ .y (COOR ¹ ) ₂ iron phosphate-oxalic acid complex compound represented by the general formula (wherein, R ¹ represents an alkyl group having 1 to 5 carbon atoms, and x is For example, when R ¹ is a methyl group and x = y = 1, the FT-IR spectrum shown in FIG. 10 and the TG shown in FIG. Having a DTA diagram and an X-ray diffraction spectrum shown in FIG. 12 (decomposition point: about 307
° C).

FePO ₄ .x (H ₂ O) ₂ .y (COO
An iron phosphate-oxalic acid complex compound represented by the general formula R ¹ ) ₂ is FePO ₄ .x (H ₂ O) ₂ .y (COO
H) The iron phosphate-oxalic acid complex compound represented by the general formula ₂ and an alcohol are preferably added in the presence of an acid in an amount of from 20 to 100.
C, more preferably at 30 to 80C. At this time, the reaction pressure is preferably normal pressure, but is not particularly limited. As a reaction solvent, a raw material alcohol can be used, but an organic solvent inert to the reaction (such as toluene) can also be used. This manufacturing method includes, for example, FePO ₄ .x (H ₂ O) ₂ .y
A preferred example is a method in which (COOH) ₂ is heated and stirred in an alcohol in the presence of an acid. FePO ₄ x generated
(H ₂ O) ₂ .y (COOR ¹ ) ₂ is separated, washed with alcohol or the like, and then dried at 70 to 200 ° C. In addition, the drying temperature is 100 ° C or more, and further 130 ° C.
As a result, water of crystallization is scattered, and x is 0 or close to 0.

As the alcohol, methanol,
1 to 1 carbon atoms such as ethanol, propanol and butanol
5 aliphatic alcohol is FePO ₄ .x (H ₂ O) ₂
1 mol or more, preferably 2 to 5 mol, more preferably ₂ to 4 mol per mol of y (COOH) ₂ . The alkyl group corresponds to R ¹ (an alkyl group having 1 to 5 carbon atoms). As the acid, for example, an inorganic acid such as hydrochloric acid, sulfuric acid, and nitric acid is used at about 0.01 to 1M.

Among the novel iron phosphate compounds, FePO_Four
X (H_TwoO)_Two・ Y (COOM) _TwoRepresented by the general formula
Iron phosphate-oxalic acid complex compound (where M is an alkali
Li metal atom or NH_FourX represents an integer of 0 to 4
And y represents an integer of 1 to 4), for example, when M is NH_Four
Group, x = y = 1, the FT-IR spectrum shown in FIG.
TG-DTA diagram shown in FIG. 14, and FIG.
Those having an X-ray diffraction spectrum (decomposition point: about 270
° C).

FePO ₄ .x (H ₂ O) ₂ .y (COO
M) ₂ is an iron phosphate-oxalic acid composite compound represented by the general formula: FePO ₄ .x (H ₂ O) ₂ .y (COOH)
It can be produced by reacting the iron phosphate-oxalic acid complex compound represented by the general formula ₂ with a basic alkali metal compound or ammonia at preferably 20 to 100 ° C, more preferably 30 to 70 ° C. it can. The reaction pressure is preferably normal pressure, but is not particularly limited. This manufacturing method includes, for example, FePO ₄ x
A preferred method is to heat and stir (H ₂ O) ₂ .y (COOH) ₂ in an aqueous solution of a basic alkali metal compound or ammonia. The generated FePO ₄ x (H
_{2 O) 2 · y (COOM} ) 2 after being separated and washed and dried at 70 to 200 ° C.. The drying temperature is 1
When the temperature is set to 00 ° C. or more, further to 130 ° C. or more, water of crystallization is scattered and x is 0 or close to 0.

Examples of the basic alkali metal compound include hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and alkali metal compounds such as lithium oxide, sodium oxide and potassium oxide. An oxide or the like is used. When M represents an alkali metal atom, M represents an alkali metal atom such as lithium, sodium, and potassium, and corresponds to an alkali metal atom in a basic alkali metal compound. 0.1 to 10% by weight of the basic alkali metal compound and ammonia,
More preferably it is used as an aqueous solution of 0.5 to 5 _{wt%, FePO 4 · x (H} 2 O) 2 · y (COO
H) ₂ preferably 2 moles or more to be more preferably 2 to 4 times by mol.

The iron phosphate-oxalic acid composite compound of the present invention is a novel compound having a catalytic function and the like. That is,
The iron phosphate-oxalic acid complex compound of the present invention has high activity oxidation (dehydrogenation) in the production of ketocarboxylic acid by oxidative dehydrogenation reaction, for example, oxidative dehydrogenation reaction of hydrocarboxylic acid (lactic acid, glycolic acid, etc.). It can be used as a catalyst.

For example, the oxidative dehydrogenation of lactic acid is carried out in a reactor filled with the iron phosphate-oxalic acid complex compound of the present invention.
It is performed in the gas phase by supplying lactic acid and molecular oxygen. At this time, the molecular oxygen is preferably supplied in an amount of 0.3 to 20 mol, more preferably 0.4 to 5 mol, per 1 mol of lactic acid,
The reaction temperature is 100 to 300 ° C, further 130 to 280 ° C
It is preferred that The reaction pressure may be any of normal pressure, increased pressure, or reduced pressure, but generally, normal pressure is appropriate. Further, the contact time is 0.1 to 20 seconds, and more preferably 0.2 to 20 seconds.
It is preferably about 10 to 10 seconds. The reaction of the present invention is not limited to the gas phase, and may be carried out, for example, in a liquid suspension system or a trickle system.

The molecular oxygen used in the oxidative dehydrogenation reaction is supplied to the reaction system as a molecular oxygen-containing gas. As the molecular oxygen-containing gas, pure oxygen gas, oxygen gas diluted with an inert gas (such as nitrogen gas), air, etc. are used. Among them, oxygen gas diluted with an inert gas (such as nitrogen gas) is used. (O ₂ concentration: 10 to 30% by volume) and air are preferably used.

In the above oxidative dehydrogenation reaction, water may be supplied to the reactor together with lactic acid or molecular oxygen to carry out the oxidative dehydrogenation reaction. Since water tends to improve the selectivity and yield of the target substance, it is preferable to supply a large amount of lactic acid, but if it is excessive, the economic efficiency is reduced. 2 for
It is preferable to supply -100 mol, more preferably 5-80 mol. Water can be supplied, for example, by heating and evaporating an aqueous lactic acid solution, or can be supplied by evaporating a necessary amount of water separately and accompanying nitrogen or the like with an inert gas. The generated pyruvic acid is separated and purified by a general method such as vacuum distillation and thin film distillation after condensing a reaction gas derived from a reactor.

[0020]

Next, the present invention will be described specifically with reference to examples and comparative examples. The following operations were performed under normal pressure unless otherwise specified.

Example 1 [Production of FePO _4. (H ₂ O) _2. (COOH) ₂ ]
Distilled water 200 ml, ferric phosphate (FePO ₄ · 2H
₂ O) 44.56 g and oxalic acid [(COOH) ₂ ] 3
7.65 g was added, and the mixture was stirred on a 70 ° C. water bath with stirring.
Heated for hours. Subsequently, the reaction solution was heated on a water bath to evaporate water, and the residue was sufficiently washed with distilled water to remove excess oxalic acid and dried at 110 ° C.

The obtained compound was analyzed by elemental analysis (Table 1), F
T-IR spectrum (FIG. 1: 1600-1700 cm ^-1)
Corresponds to a carbonyl group, and 3400-3500c
m- ¹ absorption corresponds to a hydroxyl group), thermal analysis (TG-DT
A) (FIG. 2: Weight loss of 5% by weight and 37% by weight respectively correspond to weight loss of water and oxalic acid), X-ray diffraction spectrum (FIG. 3), and redox titration (divalent Fe by XPS analysis) However, divalent F was determined by redox titration.
e was 0.2-0.3% of the total Fe)
It was an iron phosphate-oxalic acid composite compound represented by the formula of FePO _4. (H ₂ O) _2. (COOH) ₂ . The decomposition point was about 306 ° C from TG-DTA. From pyrolysis mass spectrometry (TG-MS), it was confirmed that all gases generated by decomposition of this compound were carbon dioxide gas.

Example 2 [Production of FePO _4. (COOH) ₂ ] Example 1 was repeated except that heating and stirring were performed at 80 ° C. for 10 hours.
The same operation as described above was performed. The obtained compound was an iron phosphate-oxalic acid composite compound represented by a general formula of FePO _4. (H ₂ O) _2. (COOH) ₂ , as in Example 1. Next, the compound was dried at 130 ° C. or higher for 5 hours, and then subjected to elemental analysis (Table 1), FT-IR spectrum (FIG. 4), TG-DTA (FIG. 5), X-ray diffraction spectrum (FIG. 6), and redox From the titration, it was found that FePO ₄
H) It was an iron phosphate-oxalic acid composite compound represented by the formula ₂ . The decomposition point was about 293 ° C from TG-DTA.

[0024] Example 3 _{[FePO 4 · 4 (H 2 O} ) 2 · 4 (COOH) 2 for manufacturing] distilled water 200 ml, ferric phosphate (FePO ₄ ·
2H ₂ O) 37.4 g and oxalic acid [(COOH) ₂ ] 7
2 g was added, and ultrasonic treatment was performed at 50 ° C. for 10 hours while stirring. Next, the obtained slurry was dried at 100 ° C. The obtained compound was analyzed by elemental analysis (Table 1) and FT-
From the IR spectrum (FIG. 7), TG-DTA (FIG. 8), X-ray diffraction spectrum (FIG. 9), and redox titration,
_{PO 4 · 4 (H 2 O} ) 2 · 4 (COOH) 2 comprising iron phosphate represented by the formula - was oxalic acid complex compound.

Example 4 [Production of FePO _4. (H ₂ O) _2. (COOCH ₃ ) ₂ ] The iron phosphate-oxalic acid complex compound [FePO _4. (H ₂ O) ₂
(COOH) ₂ ], and heated at 50 ° C. for 2 hours. Thereafter, methanol was distilled off from the reaction solution under reduced pressure, and the residue was dried at 100 ° C. The obtained compound was analyzed by elemental analysis (Table 1), FT-IR spectrum (FIG. 10), T
G-DTA (FIG. 11), X-ray diffraction spectrum (FIG. 1)
2) and redox titration show that FePO _4. (H ₂ O)
_The compound was an iron phosphate-oxalic acid composite compound represented by the formula ₂ · (COOCH ₃ ) ₂ . The decomposition point was about 307 ° C.

Example 5 [Production of FePO _4. (H ₂ O) _2. (COONH ₄ ) ₂ ] The iron phosphate-oxalic acid complex compound [FePO ₄ ] obtained in Example 1 was added to 20 ml of 5 wt% aqueous ammonia. ₄・ (H
₂ O) was added to ₂ · (COOH) _2] 2 g, 2 at 50 ° C.
Heated for hours. Thereafter, the reaction solution was heated on a water bath to evaporate the water, and the residue was sufficiently washed with distilled water.
And dried. The obtained compound was subjected to elemental analysis (Table 1), F
T-IR spectrum (FIG. 13), TG-DTA (FIG. 1)
4) From the X-ray diffraction spectrum (FIG. 15) and the redox titration, it was found that FePO _4. (H ₂ O) _2. (COONH ₄ )
_The compound was an iron phosphate-oxalic acid complex compound represented by Formula ₂ . The decomposition point was about 270 ° C.

[0027]

[Table 1]

Reference Example 1 [Oxidative dehydrogenation reaction of lactic acid] 20 ml of the iron phosphate-oxalic acid composite compound (granular powder) obtained in Example 3 was treated with an inner diameter of 18%.
After filling into a stainless steel reaction tube, a 10% by weight aqueous lactic acid solution (19.2 ml / mi) was added to the reaction tube under normal pressure.
n) and air (140 ml / min) while flowing
The reaction was performed at 0 ° C. for 5 hours. Lactic acid: water: air (molar ratio) = 21.3: 961: 35, and the contact time was 3.2.
Seconds. When the reaction gas was condensed and analyzed by gas chromatography, the conversion of lactic acid was 52%,
The selectivity for pyruvate was 84%.

[0029]

According to the present invention, it is possible to provide a novel iron phosphate compound (iron phosphate-oxalic acid composite compound) having a catalytic function and the like which can be used as a highly active catalyst in an oxidative dehydrogenation reaction. Further, the novel iron phosphate compound (iron phosphate-oxalic acid complex compound) of the present invention decomposes at the decomposition point to generate carbon dioxide gas.
It can be used as a carbon dioxide generator at around 00 ° C.

[Brief description of the drawings]

FIG. 1 is a composite of iron phosphate and oxalic acid obtained in Example 1.
Compound [FePO_Four・ (H_TwoO) _Two・ (COOH)_Two〕of
4 shows an FT-IR spectrum.

FIG. 2 is a composite of iron phosphate and oxalic acid obtained in Example 1.
Compound [FePO_Four・ (H_TwoO) _Two・ (COOH)_Two〕of
The TG-DTA figure is shown.

FIG. 3 [FePO _4. (H ₂ O) _2. (COOH) ₂ ] of the iron phosphate-oxalic acid composite compound obtained in Example 1
3 shows an X-ray diffraction spectrum.

FIG. 4 shows an FT-IR spectrum of the iron phosphate-oxalic acid complex compound [FePO _4. (COOH) ₂ ] obtained in Example 2.

FIG. 5 is a TG-DTA diagram of the iron phosphate-oxalic acid complex compound [FePO _4. (COOH) ₂ ] obtained in Example 2.

6 shows an X-ray diffraction spectrum of the iron phosphate-oxalic acid complex compound [FePO _4. (COOH) ₂ ] obtained in Example 2. FIG.

[7] iron phosphate obtained in Example 3 - oxalic acid complex compound _{[FePO 4 · 4 (H 2 O} ) 2 · 4 (COO
H) ₂ ].

Iron phosphate obtained in [8] Example 3 - oxalic acid complex compound _{[FePO 4 · 4 (H 2 O} ) 2 · 4 (COO
H) ₂ ] shows a TG-DTA diagram.

[9] iron phosphate obtained in Example 3 - oxalic acid complex compound _{[FePO 4 · 4 (H 2 O} ) 2 · 4 (COO
H) ₂ ].

10 shows an FT-IR spectrum of the iron phosphate-oxalic acid composite compound obtained in Example 4. FIG.

FIG. 11 shows a TG-DTA diagram of the iron phosphate-oxalic acid complex compound obtained in Example 4.

12 shows an X-ray diffraction spectrum of the iron phosphate-oxalic acid composite compound obtained in Example 4. FIG.

FIG. 13 shows an FT-IR spectrum of the iron phosphate-oxalic acid composite compound obtained in Example 5.

14 shows a TG-DTA diagram of the iron phosphate-oxalic acid composite compound obtained in Example 5. FIG.

FIG. 15 shows an X-ray diffraction spectrum of the iron phosphate-oxalic acid composite compound obtained in Example 5.

Claims (5)

[Claims] 1. An FePO ₄ .x (H ₂ O) ₂ .y (CO
X) An iron phosphate-oxalic acid complex compound represented by the general formula ₂ (wherein X represents a hydroxyl group, an alkoxy group, or an OM group, M represents an alkali metal atom or an NH ₄ group, and x
Represents an integer of 0 to 4, and y represents an integer of 1 to 4). 2. The iron phosphate-sulfur according to claim 1, wherein the iron phosphate represented by the general formula of FePO ₄ .2H ₂ O and oxalic acid are reacted at 100 ° C. or lower in the presence of water. A method for producing an acid complex compound. 3. The iron phosphate according to claim 1, wherein the iron phosphate represented by the general formula of FePO ₄ .2H ₂ O and oxalic acid are reacted at 20 to 100 ° C. in the presence of water.
A method for producing an oxalic acid composite compound. 4. An FePO ₄ · x (H ₂ O) ₂ · y (CO
OH) _{2 wherein} an iron phosphate-oxalic acid complex compound represented by the general formula: OH) ₂ is reacted with an alcohol.
ePO ₄ .x (H ₂ O) ₂ .y (COOR ¹ ) _{2 A} method for producing an iron phosphate-oxalic acid composite compound represented by the general formula (wherein R ¹ is an alkyl group having 1 to 5 carbon atoms) And x represents an integer of 0 to 4, and y represents an integer of 1 to 4). 5. An FePO ₄ · x (H ₂ O) ₂ · y (CO
FePO ₄ .x (H) characterized in that an iron phosphate-oxalic acid complex compound represented by the general formula of OH) ₂ is reacted with a basic alkali metal compound or ammonia.
₂ O) ₂ · y (COOM) _{2 A} method for producing an iron phosphate-oxalic acid complex compound represented by the general formula (where M represents an alkali metal atom or an NH ₄ group, and x represents 0 to 4) Represents an integer, and y represents an integer of 1 to 4).